Electric horn



Patented Aug.1(), 1943 UNITED ELECTRTC HORN Joe White, Anderson, Ind., assigner to Generalv Motors Corporation, Detroit, Mich., a corpora# tion of Delaware Application october 20, 1941, saranno. 415,688 Y 3 claims. (o1. lit- 7) This invention relates to electric horns comprising a flexible diaphragm having its peripheral edge clamped between a base and a projector or trumpet. The diaphragm is operated by an electromagnetic motor comprising a core supporting a winding, and anarmature connected with the diaphragm by a rod extending thru an opening in the core and base. In order to adjust the air gap thru the armature and core it has been the practice to provide for adjustably mounting the magnet core upon the base.` l

It is an object oi the invention to reducethe cost ci manufactureof horns of this type. V,In 'order to accomplish this I directly attach -the magnet core to the base, for example by electric welding, and I provide for deforming the base at a plurality of places between the magnet'core and the periphery of the base. By changingV the shape of the base at different points by pressing it toward the diaphragmv or pulling it away from the diaphragm I am able to obtain an air gapV between the armature and core which is substanf tially uniform for all practical purposes. By eliminating a separate means for adjustably mounting the core upon the base I am able to effect a material reduction in cost.

Further objects and advantages of the present invention will be apparent from the followingrde'.- Y

scription, reference being had to the accompanying drawing wherein a preferred embodiment of the present invention is clearly shown.

In the drawing:

Fig. 1 is a plan view of an electric horn embodying the present invention. i

Fig. 2 is a sectional view taken on the line 2-2 of Fig. 1.

Fig. 3 is a sectional view taken on the line 3-3 of Fig. 2.

Fig. 4 is a fragmentary view on a large scaleV showing the use of a tool for deforming the base of the horn.

Fig. 5 is a sectional View on line 5--5 of Fig. 4.

The horn comprises a diaphragm 2i] having its peripheral edge clamped by bolts 2l between a horn trumpet or projector 22 and the flange 23 of a base 24. Upon the central portion of base 24 a magnet core 25 is secured by electric welding as indicated at 26. A bracket 2l having feet 28 electrically welded to the base 24 supports armature spring 29, a contact spring and a contact bracket 3| which is insulated. Spring 33 carries a contact 32 for engaging a stationary contact 33 attached to bracket 3l.

Diaphragm 20 is centrally apertured to receive the lower end 35 of a rod 36. Rod 36 provides a i, make the base 24 more readily deformable.

shoulder 31 for receiving a washer ,33.V The Dart 35 extends thru washer 38, washer 39, the diaV phragm 23 and a stiieningvwasher ill,l then is riveted over atV 4i to securethe parts 38, 39, 20 and 40 to the rod 36. The rod Srhas a reduced upper end 62 which passes thru an armature 43. A washer 44 having a ange 45 is fitted against thesquared right hand end of armature spring 29. The ilangek 45 alsoengages the flat end of a bracket 43 havingan upper end portion il apertured atli to receive the contact spring3l. The upper endoi the part 32 is riveted at i9 to clamp the bracket 46, spring 23, vthe-,washer 44 and the armature 33 against a shoulder 53 oi the rod 33. The portion i of bracket 45 is bendable in order toadjust the spacing of the contacts 32 and 33 when the armature i3 is inits lowest position or nearest'to thecore'25.

The core 25 supports amagnet coil 5l having one end 52 connected with a terminal, not shown, and another end 53 connected with `an vkextension lla of bracket 3i .l Part Sla is connected by wire `resistance 55 isgrounded on the base Y24. This places the resistance 55 in shuntiwith the contacts 33 and 32 in order to reduce sparking'.V

vThe magnetcoilk 5i issecuredby clips'lill in. tegralwith base 2Il and `formed bypartially shearf ing away portions oi the base thus leaving apertures 6I extending a substantial distance diametrically across the base between the flange 23 thereof and the central portion 62 (Fig. 3) which receives the core 25. vThus apertures 3| tend` to purposes of changing the shape oi the base 24 in order to adjust the air gap between armature 43 and core 25, the base is provided with four holes 63 'arranged symmetrically with respect to the apertures 6l. As shown vin Fig, i on an enlarged scale each hole E53 is adapted to receive the head 64 of a tool 63. Head 34 is connected with the main portio-n oi the tool by a shank 63 eccentric with respect to the head Ei so as to providea shoulder 6l for engaging the under sideV oi the base 24, in order that the base may be pulled -up' wardly, that is, awayk from the diaphragm 2i] whensuch adjustment is required in order to 'shorten that portion oi 'the air gap which is closest to that particular hole 63 into which the tool 65 is inserted. When it is desired to lengthen the air gap the under side of the base 24 is en- 

